In riser systems for hydrocarbon exploration and production, such as in subsea operations from a vessel or exploration and production platform, coiled tubing and wire line operations, are common. These are applied for lowering equipments or measurement devices into the well or for pumping chemicals through the coil and various other operations.
Pressure control equipments are applied in coiled tubing and wire line operations for sealing around a coiled tubing or a wire line, while allowing the wire line or coiled tubing to pass down into the riser.
The riser is kept under proper tension by a tension system. This means that the vessel or platform is moving with the waves while the riser is kept substantially still. Consequently, there may be a substantive relative movement between the riser and the vessel.
A tension frame is deployed on top of the riser and is adapted to follow the movement of the riser. The tension frame is used for wire lining and coiled tubing operations into the riser. An example of a tension frame is shown in US 2005/0126790. US 2006/0196671 and US 2007/0089884 show other examples of a tension frame.
Conventionally, a tension frame is installed between a surface flow tree and a winch in the drilling or intervention tower. During wire line operations, wire line pressure control equipment is hoisted into the tension frame and connected to the top of the surface flow tree.
During coiled tubing operations, the coiled tubing pressure control equipment is lifted into the tension frame and connected to the top of the surface flow tree.
The above operations of lifting the pressure control equipment are time consuming and risky, having regard to the vertical relative motion between the tower and the riser with the tension frame.
Accordingly, there is a long felt need for a technology which ensures increased efficiency and faster as well as less complicated operation in respect of installation of pressure control equipments in tension frame during wire line and coiled tubing operations. There is also a need to avoid installing and de-installing of pressure control equipments up and down to the tension frame, on top of the surface flow tree, during such operations.
The present invention meets the abovementioned long felt need by providing a tension frame which houses at least two pressure control equipments pre-installed and parked in a ready-to-use state, one each for wire line and coiled tubing operations.